/*
 * Created on Jan 8, 2005
 * Created by Alon Rohter
 * Copyright (C) Azureus Software, Inc, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 */

package com.aelitis.azureus.core.peermanager.messaging;

import java.util.ArrayList;
import java.util.List;

import org.gudy.azureus2.core3.util.AEMonitor;
import org.gudy.azureus2.core3.util.ByteArrayHashMap;
import org.gudy.azureus2.core3.util.DirectByteBuffer;

import com.aelitis.azureus.core.peermanager.messaging.azureus.AZMessageFactory;
import com.aelitis.azureus.core.peermanager.messaging.bittorrent.BTMessageFactory;
import com.aelitis.azureus.core.peermanager.messaging.bittorrent.ltep.LTMessageFactory;

/**
 *
 */
public class MessageManager {
    private static final MessageManager instance = new MessageManager();

    private final ByteArrayHashMap message_map = new ByteArrayHashMap();
    private final List messages = new ArrayList();

    protected AEMonitor this_mon = new AEMonitor("MessageManager");

    private MessageManager() {
        /* nothing */
    }

    public static MessageManager getSingleton() {
        return instance;
    }

    /**
     * Perform manager initialization.
     */
    public void initialize() {
        AZMessageFactory.init(); // register AZ message types
        BTMessageFactory.init(); // register BT message types
        LTMessageFactory.init(); // register LT message types
    }

    /**
     * Register the given message type with the manager for processing.
     * 
     * @param message
     *            instance to use for decoding
     * @throws MessageException
     *             if this message type has already been registered
     */
    public void registerMessageType(Message message) throws MessageException {
        try {
            this_mon.enter();

            byte[] id_bytes = message.getIDBytes();

            if (message_map.containsKey(id_bytes)) {
                throw new MessageException("message type [" + message.getID() + "] already registered!");
            }

            message_map.put(id_bytes, message);

            messages.add(message);
        } finally {

            this_mon.exit();
        }
    }

    /**
     * Remove registration of given message type from manager.
     * 
     * @param message
     *            type to remove
     */
    public void deregisterMessageType(Message message) {
        try {
            this_mon.enter();

            message_map.remove(message.getIDBytes());

            messages.remove(message);
        } finally {
            this_mon.exit();
        }
    }

    /**
     * Construct a new message instance from the given message information.
     * 
     * @param id
     *            of message
     * @param message_data
     *            payload
     * @return decoded/deserialized message
     * @throws MessageException
     *             if message creation failed
     */
    public Message createMessage(byte[] id_bytes, DirectByteBuffer message_data, byte version) throws MessageException {
        Message message = (Message) message_map.get(id_bytes);

        if (message == null) {
            throw new MessageException("message id[" + new String(id_bytes) + "] not registered");
        }

        return message.deserialize(message_data, version);
    }

    /**
     * Lookup a registered message type via id and version.
     * 
     * @param id
     *            to look for
     * @return the default registered message instance if found, otherwise returns null if this message type is not registered
     */
    public Message lookupMessage(String id) {
        return (Message) message_map.get(id.getBytes());
    }

    public Message lookupMessage(byte[] id_bytes) {
        return (Message) message_map.get(id_bytes);
    }

    /**
     * Get a list of the registered messages.
     * 
     * @return messages
     */
    public Message[] getRegisteredMessages() {
        return (Message[]) messages.toArray(new Message[messages.size()]);
    }

}
